2008-2016 Microchip Technology Inc. DS20002122D-page 11
11AA02E48/11AA02E64
4.3 Write Instruction
Prior to any attempt to write data to the 11AA02EXX,
the write enable latch must be set by issuing the WREN
instruction (see Section 4.4 “Write Enable (WREN)
and Write Disable (WRDI) Instructions”).
Once the write enable latch is set, the user may
proceed with issuing a WRITE instruction (including the
header and device address bytes) followed by the MSB
and LSB of the Word Address. Once the last
Acknowledge sequence has been performed, the
master transmits the data byte to be written.
The 11AA02EXX features a 16-byte page buffer,
meaning that up to 16 bytes can be written at one time.
To utilize this feature, the master can transmit up to
16 data bytes to the 11AA02EXX, which are
temporarily stored in the page buffer. After each data
byte, the master sends a MAK, indicating whether or
not another data byte is to follow. A NoMAK indicates
that no more data is to follow, and as such will initiate
the internal write cycle.
Upon receipt of each word, the four lower-order
Address Pointer bits are internally incremented by one.
The higher-order bits of the word address remain
constant. If the master should transmit data past the
end of the page, the address counter will roll over to the
beginning of the page, where further received data will
be written.
FIGURE 4-3: WRITE COMMAND SEQUENCE
Note: If a NoMAK is generated before any data
has been provided, or if a standby pulse
occurs before the NoMAK is generated,
the 11AA02EXX will be reset, and the
write cycle will not be initiated.
Note: Page write operations are limited to
writing bytes within a single physical page,
regardless of the number of bytes
actually being written. Physical page
boundaries start at addresses that are
integer multiples of the page size
(16 bytes) and end at addresses that are
integer multiples of the page size minus 1.
As an example, the page that begins at
address 0x30 ends at address 0x3F. If a
page Write command attempts to write
across a physical page boundary, the
result is that the data wraps around to the
beginning of the current page (overwriting
data previously stored there), instead of
being written to the next page as might be
expected. It is therefore necessary for the
application software to prevent page write
operations that would attempt to cross a
page boundary.
7654
Data Byte 1
3210
7654
Data Byte 2
3210
7654
Data Byte n
3210
SCIO
MAK
MAK
No MAK
11010100
Start Header
SCIO
Device Address
MAK
00001010
MAK
Command
10101100
MAK
NoSAK
SAK
Standby Pulse
SCIO
SAK
15 14 13 12
Word Address MSB
11 10 9 8
MAK
SAK
7654
Word Address LSB
3210
MAK
SAK
SAK
SAK
SAK
Twc
